Applied sciences

Bulletin of the Polish Academy of Sciences: Technical Sciences

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Bulletin of the Polish Academy of Sciences: Technical Sciences | Early Access |

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Abstract

The paper presents the fusion approach of different feature selection methods in pattern recognition problems. The following methods are examined: nearest component analysis, Fisher discriminant criterion, refiefF method, stepwise fit, Kolmogorov-Smirnov criteria, T2-test, Kruskall-Wallis test, feature correlation with class, and SVM recursive feature elimination. The sensitivity to the noisy data as well as the repeatability of the most important features are studied. Based on this study, the best selection methods are chosen and applied in the process of selection of the most important genes and gene sequences in a dataset of gene expression microarray in prostate and ovarian cancers. The results of their fusion are presented and discussed. The small selected set of such genes can be treated as biomarkers of cancer.
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Authors and Affiliations

Fabian Gil
Stanislaw Osowski
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Epilepsy is a neurological disorder that causes seizures of many different types. The article presents an analysis of heart rate variability (HRV) for epileptic seizure prediction. Considering that HRV is nonstationary, our research focused on the quantitative analysis of a Poincare plot feature, i.e. cardiac sympathetic index (CSI). It is reported that the CSI value increases before the epileptic seizure. An algorithm using a 1D-convolutional neural network (1D-CNN) was proposed for CSI estimation. The usability of this method was checked for 40 epilepsy patients. Our algorithm was compared with the method proposed by Toichi et al. The mean squared error (MSE) for testing data was 0.046 and the mean absolute percentage error (MAPE) amounted to 0.097. The 1D-CNN algorithm was also compared with regression methods. For this purpose, a classical type of neural network (MLP), as well as linear regression and SVM regression, were tested. In the study, typical artifacts occurring in ECG signals before and during an epileptic seizure were simulated. The proposed 1D-CNN algorithm estimates CSI well and is resistant to noise and artifacts in the ECG signal.
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Authors and Affiliations

Marcin Kołodziej
Andrzej Majkowski
Paweł Tarnowski
Remigiusz Jan Rak
Andrzej Rysz
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Abstract

For brain tumour treatment plans, the diagnoses and predictions made by medical doctors and radiologists are dependent on medical imaging. Obtaining clinically meaningful information from various imaging modalities such as computerized tomography (CT), positron emission tomography (PET) and magnetic resonance (MR) scans are the core methods in software and advanced screening utilized by radiologists. In this paper, a universal and complex framework for two parts of the dose control process – tumours detection and tumours area segmentation from medical images is introduced. The framework formed the implementation of methods to detect glioma tumour from CT and PET scans. Two deep learning pre-trained models: VGG19 and VGG19-BN were investigated and utilized to fuse CT and PET examinations results. Mask R-CNN (region-based convolutional neural network) was used for tumour detection – output of the model is bounding box coordinates for each object in the image – tumour. U-Net was used to perform semantic segmentation – segment malignant cells and tumour area. Transfer learning technique was used to increase the accuracy of models while having a limited collection of the dataset. Data augmentation methods were applied to generate and increase the number of training samples. The implemented framework can be utilized for other use-cases that combine object detection and area segmentation from grayscale and RGB images, especially to shape computer-aided diagnosis (CADx) and computer-aided detection (CADe) systems in the healthcare industry to facilitate and assist doctors and medical care providers.
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Authors and Affiliations

Estera Kot
Zuzanna Krawczyk
Krzysztof Siwek
Leszek Królicki
Piotr Czwarnowski
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Abstract

This work presents an automatic system for generating kidney boundaries in computed tomography (CT) images. This paper presents the main points of medical image processing, which are the parts of the developed system. The U-Net network was used for image segmentation, which is now widely used as a standard solution for many medical image processing tasks. An innovative solution for framing the input data has been implemented to improve the quality of the learning data as well as to reduce the size of the data. Precision-recall analysis was performed to calculate the optimal image threshold value. To eliminate false-positive errors, which are a common issue in segmentation based on neural networks, the volumetric analysis of coherent areas was applied. The developed system facilitates a fully automatic generation of kidney boundaries as well as the generation of a three-dimensional kidney model. The system can be helpful for people who deal with the analysis of medical images, medical specialists in medical centers, especially for those who perform the descriptions of CT examination. The system works fully automatically and can help to increase the accuracy of the performed medical diagnosis and reduce the time of preparing medical descriptions.
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Authors and Affiliations

Tomasz Les
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Abstract

Voice acoustic analysis can be a valuable and objective tool supporting the diagnosis of many neurodegenerative diseases, especially in times of distant medical examination during the pandemic. The article compares the application of selected signal processing methods and machine learning algorithms for the taxonomy of acquired speech signals representing the vowel a with prolonged phonation in patients with Parkinson’s disease and healthy subjects. The study was conducted using three different feature engineering techniques for the generation of speech signal features as well as the deep learning approach based on the processing of images involving spectrograms of different time and frequency resolutions. The research utilized real recordings acquired in the Department of Neurology at the Medical University of Warsaw, Poland. The discriminatory ability of feature vectors was evaluated using the SVM technique. The spectrograms were processed by the popular AlexNet convolutional neural network adopted to the binary classification task according to the strategy of transfer learning. The results of numerical experiments have shown different efficiencies of the examined approaches; however, the sensitivity of the best test based on the selected features proposed with respect to biological grounds of voice articulation reached the value of 97% with the specificity no worse than 93%. The results could be further slightly improved thanks to the combination of the selected deep learning and feature engineering algorithms in one stacked ensemble model.
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Authors and Affiliations

Ewelina Majda-Zdancewicz
Anna Potulska-Chromik
Jacek Jakubowski
Monika Nojszewska
Anna Kostera-Pruszczyk
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Abstract

Recently, the analysis of medical imaging is gaining substantial research interest, due to advancements in the computer vision field. Automation of medical image analysis can significantly improve the diagnosis process and lead to better prioritization of patients waiting for medical consultation. This research is dedicated to building a multi-feature ensemble model which associates two independent methods of image description: textural features and deep learning. Different algorithms of classification were applied to single-phase computed tomography images containing 8 subtypes of renal neoplastic lesions. The final ensemble includes a textural description combined with a support vector machine and various configurations of Convolutional Neural Networks. Results of experimental tests have proved that such a model can achieve 93.6% of weighted F1-score (tested in 10-fold cross validation mode). Improvement of performance of the best individual predictor totalled 3.5 percentage points.
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Authors and Affiliations

Aleksandra Maria Osowska-Kurczab
Tomasz Markiewicz
Miroslaw Dziekiewicz
Malgorzata Lorent
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Abstract

The paper is focused on automatic segmentation task of bone structures out of CT data series of pelvic region. The authors trained and compared four different models of deep neural networks (FCN, PSPNet, U-net and Segnet) to perform the segmentation task of three following classes: background, patient outline and bones. The mean and class-wise Intersection over Union (IoU), Dice coefficient and pixel accuracy measures were evaluated for each network outcome. In the initial phase all of the networks were trained for 10 epochs. The most exact segmentation results were obtained with the use of U-net model, with mean IoU value equal to 93.2%. The results where further outperformed with the U-net model modification with ResNet50 model used as the encoder, trained by 30 epochs, which obtained following result: mIoU measure – 96.92%, “bone” class IoU – 92.87%, mDice coefficient – 98.41%, mDice coefficient for “bone” – 96.31%, mAccuracy – 99.85% and Accuracy for “bone” class – 99.92%.
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Authors and Affiliations

Zuzanna Krawczyk
Jacek Starzyński
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The article presents research on the use of Monte-Carlo Tree Search (MCTS) methods to create an artificial player for the popular card game “The Lord of the Rings”. The game is characterized by complicated rules, multi-stage round construction, and a high level of randomness. The described study found that the best probability of a win is received for a strategy combining expert knowledge-based agents with MCTS agents at different decision stages. It is also beneficial to replace random playouts with playouts using expert knowledge. The results of the final experiments indicate that the relative effectiveness of the developed solution grows as the difficulty of the game increases.
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Authors and Affiliations

Konrad Godlewski
Bartosz Sawicki
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Abstract

Boron nitride (BN) reinforced Al6061 aluminum-based composites are synthesized by conventional stir casting method followed by exposure to hot extrusion. The optical images confirmed the distribution of BN nanoparticles in the aluminum alloy matrix. The concentration of BN is varied from (0.5, 1.5, 3, 4.5, 6, 7.5, and 9 wt%) in the composites and its effect on the tensile strength was investigated. The results revealed that both extruded and heat-treated composites specimens showed enhanced toughness and tensile strength by increasing BN nanoparticle concentration. The heat-treated composite samples showed lower flexibility of up to 40%, and further, it exhibited 37% greater hardness and 32% enhancement in tensile strength over the extruded sample. The tensile properties of Al6061-BN composites were evaluated by temperature-dependent internal friction (TDIF) analysis and the results showed that the as-prepared composite's strength increased with temperature.
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Authors and Affiliations

Y.B. Mukesh
Prem Kumar Naik
Raghavendra Rao R
N.R. Vishwanatha
N.S. Prema
H.N. Girish
Naik L. Laxmana
Puttaswamy Madhusudan
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Abstract

Real time simulators of IEC 61850 compliant protection devices can be implemented without their analogue part, reducing costs and increasing versatility. Implementation of Sampled Values (SV) and GOOSE interfaces to Matlab/Simulink allows for interaction with protection relays in closed loop during power system simulation. Properly configured and synchronized Linux system with Real Time (RT) patch, can be used as a low latency run time environment for Matlab/Simulink generated model. The number of overruns during model execution using proposed SV and GOOSE interfaces with 50 µs step size is minimal. The paper discusses the implementation details and time synchronization methods of IEC 61850 real time simulator implemented in Matlab/Simulink that is built on top of run time environment shown in authors preliminary works and is the further development of them. Correct operation of the proposed solution is evaluated during the hardware-in-the-loop testing of ABB REL670 relay.
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Authors and Affiliations

Karol Kurek
Łukasz Nogal
Ryszard Kowalik
Marcin Januszewski
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Abstract

Outdoor lighting is an important element in creating an evening and nocturnal image of urban spaces. Properly designed and constructed lighting installations provide residents with comfort and security. One way to improve the energy efficiency of road lighting installation is to replace the electromagnetic control gear (ECG) with electronic ballasts (EB). The main purpose of this article is to provide an in-depth comparative analysis of the energy efficiency and performance of HPS lamps with ECG and EB. It will compare their performance under sinusoidal and nonsinusoidal voltage supply conditions for the four most commonly used HPS lamps of 70 W, 100 W, 150 W, and 250 W. The number of luminaires supplied from one circuit was determined based on the value of permissible active power losses. With the use of the DIALux program, projects of road lighting installation were developed. On this basis, energy performance indicators, electricity consumption, electricity costs, and CO 2 emissions were calculated for one-phase and three-phase installations. The obtained results indicate that an HPS lamp with EB is better than an HPS lamp with ECG in terms of energy quality, energy savings, and environmental impact. The results of this analysis are expected to assist in the choice of HPS lighting technology.
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Authors and Affiliations

Roman Sikora
Przemysław Markiewicz
Paweł Rózga
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The paper presents the first vertical-cavity surface-emitting lasers (VCSELs) designed, grown, processed and evaluated entirely in Poland. The lasers emit at »850 nm, which is the most commonly used wavelength for short-reach (<2 km) optical data communication across multiple-mode optical fiber. Our devices present state-of-the-art electrical and optical parameters, e.g. high room-temperature maximum optical powers of over 5 mW, laser emission at heat-sink temperatures up to at least 95°C, low threshold current densities (<10 kA/cm2) and wall-plug efficiencies exceeding 30% VCSELs can also be easily adjusted to reach emission wavelengths of around 780 to 1090 nm.
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Authors and Affiliations

Marcin Gębski
Patrycja Śpiewak
Walery Kołkowski
Iwona Pasternak
Weronika Głowadzka
Włodzimierz Nakwaski
Robert P. Sarzała
Michał Wasiak
Tomasz Czyszanowski
Włodzimierz Strupiński
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Abstract

The optimum combination of blade angle of the runner and guide vane opening with Kaplan turbine can improve the hydroelectric generating the set operation efficiency and the suppression capability of oscillations. Due to time and cost limitations and the complex operation mechanism of the Kaplan turbine, the coordination test data is insufficient, making it challenging to obtain the whole curves at each head under the optimum coordination operation by field tests. The field test data is employed to propose a least-squares support vector machine (LSSVM)-based prediction model for Kaplan turbine coordination tests. Considering the small sample characteristics of the test data of Kaplan turbine coordination, the LSSVM parameters are optimized by an improved grey wolf optimization (IGWO) algorithm with mixed non-linear factors and static weights. The grey wolf optimization (GWO) algorithm has some deficiencies, such as the linear convergence factor, which inaccurately simulates the actual situation, and updating the position indeterminately reflects the absolute leadership of the leader wolf. The IGWO algorithm is employed to overcome the aforementioned problems. The prediction model is simulated to verify the effectiveness of the proposed IGWO-LSSVM. The results show high accuracy with small samples, a 2.59% relative error in coordination tests, and less than 1.85% relative error in non-coordination tests under different heads.
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Authors and Affiliations

Fannie Kong
Jiahui Xia
Daliang Yang
Ming Luo
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Abstract

The research was attempted to mimic the locomotion of the salamander, which is found to be one of the main animals from an evolutionary point of view. The design of the limb and body was started with the parametric studies of pneumatic network (Pneu-Net). Pneu-Net is a pneumatically operated soft actuator that bends when compressed fluid is passed inside the chamber. Finite Element Analysis software, ANSYS, was used to evaluate the height of the chamber, number of chambers and the gap between chambers for both limb and body of the soft mechanism. The parameters were decided based on the force generated by the soft actuators. The assembly of the salamander robot was then exported to MATLAB for simulating the locomotion of the robot in a physical environment. Sine-based controller was used to simulate the robot model and the fastest locomotion of the salamander robot was identified at 1 Hz frequency, 0.3 second of signal delay for limb actuator and negative π phase difference for every contralateral side of the limbs. Shin-Etsu KE-1603, a hyper elastic material, was used to build the salamander robot and a series of experiments were conducted to record the bending angle, the respective generated force in soft actuators and the gait speed of the robot. The developed salamander robot was able to walk at 0.06774 m/s, following an almost identical pattern to the simulation.
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Authors and Affiliations

Elango Natarajan
Kwang Y. Chia
Ahmad Athif Mohd Faudzi
Wei Hong Lim
Chun Kit Ang
Ali Jafaari
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Abstract

Nowadays in e-commerce applications, aspect-based sentiment analysis has become vital, and every consumer started focusing on various aspects of the product before making the purchasing decision on online portals like Amazon, Walmart, Alibaba, etc. Hence, the enhancement of sentiment classification considering every aspect of products and services is in the limelight. In this proposed research, an aspect-based sentiment classification model has been developed employing sentiment whale-optimized adaptive neural network (SWOANN) for classifying the sentiment for key aspects of products and services. The accuracy of sentiment classification of the product and services has been improved by the optimal selection of weights of neurons in the proposed model. The promising results are obtained by analyzing the mobile phone review dataset when compared with other existing sentiment classification approaches such as support vector machine (SVM) and artificial neural network (ANN). The proposed work uses key features such as the positive opinion score, negative opinion score, and term frequency-inverse document frequency (TF-IDF) for representing each aspect of products and services, which further improves the overall effectiveness of the classifier. The proposed model can be compatible with any sentiment classification problem of products and services.
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Authors and Affiliations

Nallathambi Balaganesh
K. Muneeswaran
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Abstract

The paper presents the results of research on the influence of the parameters of Fused Deposition Modelling (FDM) on the mechanical properties and geometric accuracy of angle-shaped parts. The samples were manufactured from acrylonitrile butadiene styrene (ABS) on a universal machine. A complete factorial experiment was conducted. The results indicated that the critical technological parameter was the angular orientation of the sample in the working chamber of the machine. The results were compared with the results of research performed on simple rectangular samples. A significant similarity was found in the relationships between the FDM parameters and properties for both sample types.
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Authors and Affiliations

Wiesław Kuczko
Adam Hamrol
Radosław Wichniarek
Filip Górski
Michał Rogalewicz
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Abstract

Adsorption cooling and desalination technologies have recently received more attention. Adsorption chillers, using eco-friendly refrigerants, provide promising abilities for low-grade waste heat recovery and utilization, especially renewable and waste heat of the near ambient temperature. However, due to the low coefficient of performance (COP) and cooling capacity (CC) of the chillers, they have not been widely commercialized. Although operating in combined heating and cooling (HC) systems, adsorption chillers allow more efficient conversion and management of low-grade sources of thermal energy, their operation is still not sufficiently recognized, and the improvement of their performance is still a challenging task. The paper introduces an artificial intelligence (AI) approach for the optimization study of a two-bed adsorption chiller operating in an existing combined HC system, driven by low-temperature heat from cogeneration. Artificial neural networks are employed to develop a model that allows estimating the behavior of the chiller. Two crucial energy efficiency and performance indicators of the adsorption chiller, i.e., CC and the COP, are examined during the study for different operating sceneries and a wide range of operating conditions. Thus this work provides useful guidance for the operating conditions of the adsorption chiller integrated into the HC system. For the considered range of input parameters, the highest CC and COP are equal to 12.7 and 0.65 kW, respectively. The developed model, based on the neurocomputing approach, constitutes an easy-to-use and powerful optimization tool for the adsorption chiller operating in the complex HC system.
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Authors and Affiliations

Jarosław Krzywanski
Karol Sztekler
Marcin Bugaj
Wojciech Kalawa
Karolina Grabowska
Patryk Robert Chaja
Marcin Sosnowski
Wojciech Nowak
Łukasz Mika
Sebastian Bykuć
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Abstract

The paper presents and sums up the research and technical aspects of the modernization of the cutting tool of the dredger. Improper adjustment of the cutting elements not adjusted to the characteristics of excavated material is not an uncommon situation, causing versatile geological conditions. Relocation of the machines from one pit to another may result in the significant influence on the excavation process (wear, output, etc.). Common practice is the field try and error approach to obtain desired machine performance. In the paper authors present the approach with aid of cutting-edge technologies. Coupled DEM and kinematic simulations supported by the reverse engineering technologies of laser scanning were the fundamental drivers for final adjustments of the cutting tool at its present operational conditions.
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Authors and Affiliations

Jakub Andruszko
Przemyslaw Moczko
Damian Pietrusiak
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Abstract

Bridge inspections are a vital part of bridge maintenance and the main information source for Bridge Management Systems is used in decision-making regarding repairs. Without a doubt, both can benefit from the implementation of the Building Information Modelling philosophy. To fully harness the BIM potential in this area, we have to develop tools that will provide inspection accurate information easily and fast. In this paper, we present an example of how such a tool can utilise tablets coupled with the latest generation RGB D cameras for data acquisition; how these data can be processed to extract the defect surface area and create a 3D representation, and finally embed this information into the BIM model. Additionally, the study of depth sensor accuracy is presented along with surface area accuracy tests and an exemplary inspection of a bridge pillar column.
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Authors and Affiliations

Bartosz Wójcik
Mateusz Żarski
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Abstract

This paper presents a new approach to the design methodology of road routes, in literature often referred to as the polynomial alignment. The author proposes the use of the so-called general transition curves that have been described in detail in his earlier research papers. General transition curves employ only one curvature extremum, and the whole curved transition between two extreme points of zero curvature value is described by a single equation. As a result, the curves are very useful for the creation of route geometry in accordance with the principles of polynomial alignment. The paper describes the main concept of polynomial alignment and presents equations of curves which can be used in the proposed alignment procedure. In addition, the paper gives a detailed description of design procedures.
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Authors and Affiliations

Andrzej Kobryń
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Abstract

This article considers the problem of the rise in temperature of the windings of an induction motor during start-up. Excessive growth of thermal stresses in the structure of a cage winding increases the probability of damage to the winding of the rotor. For the purpose of analysis of the problem, simplified mathematical relationships are given, enabling the comparison of quantities of energy released in a rotor winding during start-up by different methods. Also, laboratory tests were carried out on a specially adapted cage induction motor enabling measurement of the temperature of a rotor winding during its operation. Because there was no possibility of investigating motors in medium- and high-power drive systems, the authors decided to carry out tests on a low-power motor. The study concerned the start-up of a drive system with a 4 kW cage induction motor. Changes in the winding temperature were recorded for three cases: direct online start-up, soft starting, and the use of a variable-frequency drive (VFD). Conclusions were drawn based on the results obtained. In high-power motors, the observed phenomena occur with greater intensity, because of the use of deep bar and double cage rotors. For this reason, indication is made of the particular need for research into the energy aspects of different start-up methods for medium- and high-power cage induction motors in conditions of prolonged start-up.
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Authors and Affiliations

Jan Mróz
Piotr Bogusz
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Abstract

Due to the coexistence of continuity and discreteness, energy management of a multi-mode power split hybrid electric vehicle (HEV) can be considered a typical hybrid system. Therefore, the hybrid system theory is applied to investigate the optimum energy distribution strategy of a power split multi-mode HEV. In order to obtain a unified description of the continuous/discrete dynamics, including both the steady power distribution process and mode switching behaviors, mixed logical dynamical (MLD) modeling is adopted to build the control-oriented model. Moreover, linear piecewise affine (PWA) technology is applied to deal with nonlinear characteristics in MLD modeling. The MLD model is finally obtained through a high level modeling language, i.e. HYSDEL. Based on the MLD model, hybrid model predictive control (HMPC) strategy is proposed, where a mixed integer quadratic programming (MIQP) problem is constructed for optimum power distribution. Simulation studies under different driving cycles demonstrate that the proposed control strategy can have a superior control effect as compared with a rule-based control strategy.
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Authors and Affiliations

Shaohua Wang
Sheng Zhang
Dehua Shi
Xiaoqiang Sun
T. Yang
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Abstract

Magnetic nanoparticle’s different applications in nanomedicine, due to their unique physical properties and biocompatibility, were intensively investigated. Recently, Fe₃O₄ nanoparticles, are confirmed to be the best sonosensitizers to enhance the performance of HIFU (high intensity focused ultrasound). They are also used as thermo-sensitizers in magnetic hyperthermia. A new idea of dual, magneto-ultrasound, coupled hyperthermia allows the ultrasound intensity to be reduced from the high to a moderate level. Our goal is to evaluate the enhancement of thermal effects of focused ultrasound of moderate intensity due to the presence of nanoparticles. We combine experimental results with numerical analysis. Experiments are performed on tissue-mimicking materials made of the 5% agar gel and gel samples containing Fe₃O₄ nanoparticles with φ  = 100 nm with two fractions of 0.76 and 1.53% w/w. Thermocouples registered curves of temperature rising during heating by focused ultrasound transducer with acoustic powers of the range from 1 to 4 W. The theoretical model of ultrasound-thermal coupling is solved in COMSOL Multiphysics. We compared the changes between the specific absorption rates (SAR) coefficients determined from the experimental and numerical temperature rise curves depending on the nanoparticle fractions and applied acoustic powers.We confirmed that the significant role of nanoparticles in enhancing the thermal effect is qualitatively similarly estimated, based on experimental and numerical results. So that we demonstrated the usefulness of the FEM linear acoustic model in the planning of efficiency of nanoparticle-mediated moderate hyperthermia.
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Authors and Affiliations

Barbara Gambin
Eleonora Kruglenko
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Abstract

The artificial bee colony (ABC) algorithm is well known and widely used optimization method based on swarm intelligence, and it is inspired by the behavior of honeybees searching for a high amount of nectar from the flower. However, this algorithm has not been exploited sufficiently. This research paper proposes a novel method to analyze the exploration and exploitation of ABC. In ABC, the scout bee searches for a source of random food for exploitation. Along with random search, the scout bee is guided by a modified genetic algorithm approach to locate a food source with a high nectar value. The proposed algorithm is applied for the design of a nonlinear controller for a continuously stirred tank reactor (CSTR). The statistical analysis of the results confirms that the proposed modified hybrid artificial bee colony (HMABC) achieves consistently better performance than the traditional ABC algorithm. The results are compared with conventional ABC and nonlinear PID (NLPID) to show the superiority of the proposed algorithm. The performance of the HMABC algorithm-based controller is competitive with other state-of-the-art meta-heuristic algorithm-based controllers in the literature.
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Authors and Affiliations

Nedumal P. Pugazhenthi
S. Selvaperumal
K. Vijayakumar
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Abstract

The main drawback of any Design for Reliability methodology is lack of easy accessible reliability models, prepared individually for each critical component. In this paper, a reliability model for SiC power MOSFET in SOT – 227 B housing, subjected to power cycling, is presented. Discussion covers preparation of Accelerated Lifetime Test required to develop such reliability model, analysis of semiconductor degradation progress, samples post-failure analysis and identification of reliability model parameters. Such model may be further used for failure prognostics or useful lifetime estimation of High Performance Power Supplies.
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Authors and Affiliations

Sebastian Bąba
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Abstract

In the ceramic industry, quality control is performed using visual inspection in three different product stages: green, biscuit, and the final ceramic tile. To develop a real-time computer visual inspection system, the necessary step is successful tile segmentation from its background. In this paper, a new statistical multi-line signal change detection (MLSCD) segmentation method based on signal change detection (SCD) method is presented. Through experimental results on seven different ceramic tile image sets, MLSCD performance is analyzed and compared with the SCD method. Finally, recommended parameters are proposed for optimal performance of the MLSCD method.
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Authors and Affiliations

Filip Sušac
Tomislav Matić
Ivan Aleksi
Tomislav Keser
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Abstract

To improve the curve driving stability and safety under critical maneuvers for four-wheel-independent drive autonomous electric vehicles, a three-stage direct yaw moment control (DYC) strategy design procedure is proposed in this work. The first stage conducts the modeling of the tire nonlinear mechanical properties, i.e. the coupling relationship between the tire longitudinal force and the tire lateral force, which is crucial for the DYC strategy design, in the STI (Systems Technologies Inc.) form based on experimental data. On this basis, a 7-DOF vehicle dynamics model is established and the direct yaw moment calculation problem of the four-wheel-independent drive autonomous electric vehicle is solved through the nonsingular fast terminal sliding mode (NFTSM) control method, thus the optimal direct yaw moment can be obtained. To achieve this direct yaw moment, an optimal allocation problem of the tire forces is further solved by using the trust-region interior-point method, which can effectively guarantee the solving efficiency of complex optimization problem like the tire driving and braking forces allocation of four wheels in this work. Finally, the effectiveness of the DYC strategy proposed for the autonomous electric vehicles is verified through the CarSim-Simulink co-simulation results.
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Authors and Affiliations

Xiaoqiang Sun
Yujun Wang
Yingfeng Cai
Pak Kin Wong
Long Chen
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Abstract

For fault detection of doubly-fed induction generator (DFIG), in this paper, a method of sliding mode observer (SMO) based on a new reaching law (NRL) is proposed. The SMO based on the NRL (NRL- SMO) theoretically eliminates system chatter caused by the reaching law and can be switched in time with system interference in terms of robustness and smoothness. In addition, the sliding mode control law is used as the index of fault detection. Firstly, this paper gives the NRL with the theoretically analyzes. Secondly, according to the mathematical model of DFIG, NRL-SMO is designed, and its analysis of stability and robustness are carried out. Then this paper describes how to choose the optimal parameters of the NRL-SMO. Finally, three common wind turbine system faults are given, which are DFIG inter-turn stator fault, grid voltage drop fault, and rotor current sensor fault. The simulation models of the DFIG under different faults is established. The simulation results prove that the superiority of the method of NRL-SMO in state tracking and the feasibility of fault detection.
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Authors and Affiliations

RuiQi Li
Wenxin Yu
JunNian Wang
Yang Lu
Dan Jiang
GuoLiang Zhong
ZuanBo Zhou
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Abstract

The synchronisation of a complex chaotic network of permanent magnet synchronous motor systems has increasing practical importance in the field of electrical engineering. This article presents the control design method for the hybrid synchronization and parameter estimation of ring-connected complex chaotic network of permanent magnet synchronous motor systems. The design of the desired control law is a challenging task for control engineers due to parametric uncertainties and chaotic responses to some specific parameter values. Controllers are designed based on the adaptive integral sliding mode control to ensure hybrid synchronization and estimation of uncertain terms. To apply the adaptive ISMC, firstly the error system is converted to a unique system consisting of a nominal part along with the unknown terms which are computed adaptively. The stabilizing controller incorporating nominal control and compensator control is designed for the error system. The compensator controller, as well as the adopted laws, are designed to get the first derivative of the Lyapunov equation strictly negative. To give an illustration, the proposed technique is applied to 4-coupled motor systems yielding the convergence of error dynamics to zero, estimation of uncertain parameters, and hybrid synchronization of system states. The usefulness of the proposed method has also been tested through computer simulations and found to be valid.
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Authors and Affiliations

Nazam Siddique
Fazal U. Rehman
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Abstract

The article deals with studying the hydrodynamic characteristics of the fluidized bed in gravitation shelf dryers. The algorithm to calculate hydrodynamic characteristics of the fluidized bed in the dryer’s workspace is described. Every block of the algorithm has a primary hydrodynamic characteristics theoretical model of calculation. Principles of disperse phase motion in various areas in the gravitation shelf dryer are established. The software realization of the author’s mathematic model to calculate disperse phase motion trajectory in a free and constrained regime, disperse phase residence time in the dryers’ workspace, polydisperse systems classification is proposed in the study. Calculations of disperse phase motion hydrodynamic characteristics using the software product ANSYS CFX, based on the author’s mathematic model, are presented in the article. The software product enables automating calculation simultaneously by several optimization criteria and visualizing calculation results in the form of 3D images. The disperse phase flow velocity fields are obtained; principles of a wide fraction of the disperse phase distribution in the workspace of the shelf dryer are fixed. The way to define disperse phase residence time91 in the workspace of the shelf dryer in free (without consideration of cooperation with other particles and dryer’s elements) and con-strained motion regimes is proposed in the research. The calculation results make a base for the optimal choice of the gravitation shelf dryer working chamber sizes.
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Authors and Affiliations

Nadiia Artyukhova
Jan Krmela
Vladimíra Krmelová
Artem Artyukhov
Mária Gavendová
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Abstract

In times of the COVID-19, reliable tools to simulate the airborne pathogens causing the infection are extremely important to enable the testing of various preventive methods. Advection-diffusion simulations can model the propagation of pathogens in the air. We can represent the concentration of pathogens in the air by “contamination” propagating from the source, by the mechanisms of advection (representing air movement) and diffusion (representing the spontaneous propagation of pathogen particles in the air). The three-dimensional time-dependent advection-diffusion equation is difficult to simulate due to the high computational cost and instabilities of the numerical methods. In this paper, we present alternating directions implicit isogeometric analysis simulations of the three-dimensional advection-diffusion equations. We introduce three intermediate time steps, where in the differential operator, we separate the derivatives concerning particular spatial directions. We provide a mathematical analysis of the numerical stability of the method. We show well-posedness of each time step formulation, under the assumption of a particular time step size. We utilize the tensor products of one-dimensional B-spline basis functions over the three-dimensional cube shape domain for the spatial discretization. The alternating direction solver is implemented in C++ and parallelized using the GALOIS framework for multi-core processors. We run the simulations within 120 minutes on a laptop equipped with i7 6700 Q processor 2.6 GHz (8 cores with HT) and 16 GB of RAM.
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Authors and Affiliations

Marcin Łoś
Maciej Woźniak
Ignacio Muga
Maciej Paszynski
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Abstract

We analyze the Google-Apple exposure notification mechanism designed by the Apple-Google consortium and deployed on a large number of Corona-warn apps. At the time of designing it, the most important issue was time-to-market and strict compliance with the privacy protection rules of GDPR. This resulted in a plain but elegant scheme with a high level of privacy protection. In this paper we go into details and propose some extensions of the original design addressing practical issues. First, we point to the danger of a malicious cryptographic random number generator (CRNG) and resulting possibility of unrestricted user tracing. We propose an update that enables verification of unlinkability of pseudonymous identifiers directly by the user. Second, we show how to solve the problem of verifying the “same household” situation justifying exempts from distancing rules. We present a solution with MIN-sketches based on rolling proximity identifiers from the Apple-Google scheme. Third, we examine the strategies for revealing temporary exposure keys. We detect some unexpected phenomena regarding the number of keys for unbalanced binary trees of a small size. These observations may be used in case that the size of the lists of diagnosis keys has to be optimized.
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Authors and Affiliations

Adam Bobowski
Jacek Cichoń
Mirosław Kutyłowski
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Abstract

Efforts of the scientific community led to the development of multiple screening approaches for COVID-19 that rely on machine learning methods. However, there is a lack of works showing how to tune the classification models used for such a task and what the tuning effect is in terms of various classification quality measures. Understanding the impact of classifier tuning on the results obtained will allow the users to apply the provided tools consciously. Therefore, using a given screening test they will be able to choose the threshold value characterising the classifier that gives, for example, an acceptable balance between sensitivity and specificity. The presented work introduces the optimisation approach and the resulting classifiers obtained for various quality threshold assumptions. As a result of the research, an online service was created that makes the obtained models available and enables the verification of various solutions for different threshold values on new data.
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Authors and Affiliations

Michał Kozielski
Joanna Henzel
Joanna Tobiasz
Aleksandra Gruca
Paweł Foszner
Joanna Zyla
Małgorzata Bach
Aleksandra Werner
Jerzy Jaroszewicz
Joanna Polańska
Marek Sikora
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Abstract

In the paper, we are analyzing and proposing an improvement to current tools and solutions for supporting fighting with COVID-19. We analyzed the most popular anti-covid tools and COVID prediction Models. We addressed issues of secure data collection, prediction accuracy based on COVID models. What is most important, we proposed a solution for improving the prediction and contract tracing element in these applications. The proof of concept solution to support the fight against a global pandemic is presented, and the future possibilities for its development are discussed.
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Authors and Affiliations

Martyna Gruda
Michal Kedziora
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Abstract

The aim of the work was to discuss the behavior of the proprietary Real-Time Simulator (RTS) during testing coordination of distance relay protections in power engineering. During the construction process of the simulator, the mapping of various dynamic phenomena occurring in the modeled part of the power system was taken into account. Solution main asset is lower cost of construction while maintaining high values of essential parameters, based on the generally available software environment (MATLAB/Simulink). The obtained results were discussed in detail. This work is important from the point of view of the cost-effectiveness concerning design procedures especially important in power systems exploitation and avoiding faults that result from the selection of protection relay devices, electrical devices, system operation, and optimization of operating conditions. The manuscript carefully discusses the hardware configuration and sample results, so that the presented real-time simulator can be reproduced by another researcher.
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Authors and Affiliations

Adam Smolarczyk
Sebastian Łapczyński
Michał Szulborski
Łukasz Kolimas
Łukasz Kozarek
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Abstract

Appropriate modeling of unsteady aerodynamic characteristics is required for the study of aircraft dynamics and stability analysis, especially at higher angles of attack. The article presents an example of using artificial neural networks to model such characteristics. The effectiveness of this approach was demonstrated on the example of a strake-wing micro aerial vehicle. The neural model of unsteady aerodynamic characteristics was identified from the dynamic test cycles conducted in the water tunnel. The aerodynamic coefficients were modeled as function of the flow parameters. The article presents neural models of longitudinal aerodynamic coefficients: lift and pitching moment as functions of angles of attack and reduced frequency. The modeled and trained aerodynamic coefficients show good consistency. This method shows great potential in the construction of aerodynamic models for flight simulation purposes.
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Authors and Affiliations

Dariusz Rykaczewski
Mirosław Nowakowski
Krzysztof Sibilski
Wiesław Wróblewski
Michał Garbowski
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Abstract

Polyester coatings are among the most commonly used types of powder paints and present a wide range of applications. Apart from its decorative values polyester coating successfully prevents the substrate from environmental deterioration. This work investigates the cavitation erosion (CE) resistance of three commercial polyester coatings electrostatic spray onto AW-6060 aluminium alloy substrate. Effect of coatings repainting (single- and double-layer deposits) and effect of surface finish (matt, silk gloss and structural) on resistance to cavitation were comparatively studied. The following research methods were used: CE testing using ASTM G32 procedure, 3D profilometry evaluation, light optical microscopy, scanning electron microscopy, optical profilometry and FTIR spectroscopy. Electrostatic spray coatings present higher CE resistance than aluminium alloy. The matt finish double-layer (M2) and single-layer silk gloss finish (S1) are the most resistant to CE. The structural paint showed the lowest resistance to cavitation wear which derives from the rougher surface finish. The CE mechanism of polyester coatings relies on the material brittle-ductile behaviour, cracks formation, lateral net-cracking growth and removal of chunk coating material and craters’ growth. Repainting does not harm the properties of the coatings. Therefore, it can be utilised to regenerate or smother the polyester coating finish along with improvement of their CE resistance.
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Authors and Affiliations

Mirosław Szala
Aleksander Świetlicki
Weronika Sofińska-Chmiel
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Abstract

Elements of the lightning protection system (LPS) often also perform other functions in the facility. Correct and economical design of these elements is possible with the fulfillment of specific requirements, close coordination and inter-branch cooperation. The article draws attention to important aspects of the LPS design and highlights the ambiguities that may arise during this process. Firstly, the history of changes in national standardisation in the field of lightning protection is approximated. Secondly, the individual components of the external LPS are presented. Subsequently, the normative material requirements for earthing are compiled, depending on their function (for lightning protection and protection against electric shock in MV and LV installations). The last part of the paper is devoted to the comparison of the protective angle method and the rolling sphere method. The analysis was made on the example of a simple object for which the LPS class I is required. It has been shown that despite the possibility of using both methods, they may result in different solutions. Depending on the choice of method, the difference in the arrangement of the air-termination system is indicated. Examples of generally available LPS solutions are also given, taking into account various materials and assembly technologies.
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Authors and Affiliations

Anna Dąda
Paweł Błaut
Piotr Miller
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Abstract

The article deals with the technological principles regarding the final drying process of the porous ammonium nitrate (PAN) granules in multistage gravitational shelf dryers. The data on the dryer’s optimal technological operating modes are obtained. PAN samples are studied; the regularity of the porous structure change in the granule depending on the dryer’s hydrodynamic and thermodynamic conditions is established. Experimental data obtained during the research will be used to create a methodology for the engineering calculation of gravitational shelf dryers. Moreover, the data on the optimal operating conditions of the drying machines at the final drying stage will be used to improve the technology to form porous granules from agricultural ammonium nitrate.
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Authors and Affiliations

Nadiia Artyukhova
Jan Krmela
Artem Artyukhov
Vladimíra Krmelová
Mária Gavendová
Alžbeta Bakošová
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Abstract

In this paper thermal oxidation resistance of the silicide coated niobium substrates was tested in temperature range 1300÷1450°C using HVOF burner. Pure niobium specimens were coated using pack cementation CVD method. Three different silicide thickness coatings were deposited. Thermal oxidation resistance of the coated niobium substrates was tested in temperature range 1300÷1450°C using HVOF burner. All samples that passed the test showed their ability to stabilize the temperature in time of 30 s during the thermal test. The rise time of substrate temperature takes about 10 s after which keeps constant values. In order to assess the quality of the Nb-Si coatings before and after the thermal test, a light microscopy, Scanning Electron Microscopy (SEM) and chemical analysis (EDS), X-ray diffraction XRD and Vickers hardness test investigation were performed. Results confirmed the presence of substrate compounds Nb as well as Si addition. The oxygen compounds are result of high temperature intense oxidizing environment that causes the generation of SiO phase in the form of quartz and cristobalite during thermal test. Except one specimen all substrates surfaces pass the high temperature oxidation test with no damages.
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Authors and Affiliations

Radoslaw Szklarek
Tomasz Tanski
Boguslaw Mendala
Marcin Staszuk
Lukasz Krzeminski
Pawel Nuckowski
Kamil Sobczak
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Abstract

In this scientific publication, research results of two newly developed hot-rolled Fe-Mn-Al-C (X105) and Fe-Mn-Al-Nb-Ti-C (X98) steels were compared. These steels are characterized by an average density of 6.68 g/cm3, a value 15% lower compared to the conventional structural steels. Hot rolling was carried out on a semi-industrial line to evaluate the effect of hot plastic deformation conditions with different cooling variants on the structure. The detailed analysis of the phase composition as well as the microstructure allows to state that the investigated steels are characterized by austenitic-ferritic structure with carbides precipitates. The results of the transmission electron microscopy (TEM) tests of both steels after hot rolling showed the occurrence of various deformation effects such as shear bands, micro bands and lens twins in the microstructure. Based on the research undertaken with the use of transmission electron microscopy, it was found that the hardening mechanism of the X98 and X105 steels is deformation-induced plasticity by the formation of shear bands (SIP) and micro shear bands (MBIP).
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Authors and Affiliations

Liwia Sozańska-Jędrasik
Wojciech Borek
Janusz Mazurkiewicz
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Abstract

The S304H steel is used in the construction of pressure components of boilers with supercritical operating parameters. The paper presents the results of the research on the microstructure after ageing for 30,000 hours at 650 and 700°C. The microstructure examination was performed using scanning and transmission electron microscopy. The precipitates were identifies using transmission electron microscopy. The paper analyses the precipitation process and its dynamics depending on the temperature and ageing time in detail. The MX carbonitrides and the ε_Cu phase were shown to be the most stable phase, regardless of the test temperature. It was also showed that the M 23C 6 carbide precipitates in the tested steel and the intermetallic sigma phase (σ) may play a significant role in the loss of durability of the tested steel. It is related to their significant increase due to the influence of elevated temperature, and their coagulation and coalescence dynamics strongly depend on the ageing/operating temperature level. The qualitative and quantitative identification of the secondary phase precipitation processes described in the study is important in the analysis of the loss of durability of the tested steel under creep conditions.
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Authors and Affiliations

Adam Zieliński
Robert Wersta
Marek Sroka
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Abstract

The growing interest in one-dimensional tin oxide-based nanomaterials, boost research in both high-quality nanomaterials as well as in production methods. This is due to the fact that they present unique electrical and optical properties, that enable their application in various (opto)electronic devices. Thus, the aim of the paper was to produce ceramic SnO₂ nanowires using electrospinning with calcination method and to investigate the influence of the calcination temperature on the morphology, structure, and optical properties of the obtained material. A scanning electron microscope (SEM)) and Fourier-transform infrared spectroscopy (FTIR) were used to examine the morphology and chemical structure of obtained nanomaterials. The optical properties of manufactured one-dimensional nanostructures were investigated using UV–Vis spectroscopy. Moreover, based on the UV–Vis spectra, the energy band gap of the prepared nanowires was determined. The analysis of the morphology of the obtained nanowires showed that both the concentration of the precursor in the spinning solution and the calcination temperature have a significant impact on the diameter of the nanowires and, consequently, on their optical properties.
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Authors and Affiliations

Tomasz Tański
Weronika Smok
Wiktor Matysiak
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Abstract

Magnesium alloys are recently more and more popular in many sectors of the industry due to their unique properties, such as low density, high specific strength, vibration damping ability, also their recyclability, and excellent machinability. Nowadays, thin films have been attracting more attention in applications that improve mechanical and corrosion properties. The following alloys were used for the coated: Mg-Al-RE and the ultra-light magnesium-lithium alloy of the Mg-Li-Al-RE type. A single layer of TiO₂ was deposited using the atomic layer deposition ALD method. Multilayer layers of the Ti/TiO₂ and Ti/TiO₂/Ti/TiO₂ type were obtained by the MS-PVD magnetron sputtering technique. Samples were investigated by scanning and transmission electron microscope (SEM, TEM) and their morphology by atomic forces microscope (AFM). Further examinations like electrochemical corrosion, roughness, and tribology were carried out. As a result of the research, it was found that the best electrochemical properties are exhibited by single TiO₂ layers obtained by the ALD method. Moreover, it was found that Ti/TiO₂/Ti/TiO₂ double film has better properties than Ti/TiO₂ film.
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Authors and Affiliations

Marcin Staszuk
Łukasz Reimann
Aleksandra Ściślak
Justyna Jaworska
Mirosława Pawlyta
Tomasz Mikuszewski
Dariusz Kuc
Tomasz Tański
Antonín Kříž
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Abstract

Magnesium-based alloys are widely used in the construction of the automotive, aviation and medical industries. There are many parameters that can be modified during the synthesis in order to obtain an alloy with the desired microstructure and advantageous properties. Modifications to the chemical composition and parameters of the synthesis process are of key importance. In this work, Mg-based alloy with a rare-earth element addition was synthesized by mechanical alloying (MA). The aim of this work was to study the effect of milling times on Mg based alloy with a rare-earth addition on the structure and microhardness. A powder mixture of pure elements was milled in a SPEX 8000D high energy shaker ball mill under an argon atmosphere using a stainless steel container and balls. The sample was mechanically alloyed at milling times: 3, 5, 8 and 13 h with 0.5 h interruptions. The microstructure and hardness of samples were investigated. The Mg-based powder alloy was examined by an X-ray diffraction (XRD), scanning electron microscopy (SEM) and a Vickers microhardness test. The results showed that the microhardness of the sample milled for 13 h was higher than that of milling time of 3, 5 and 8 h.
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Authors and Affiliations

Sabina Lesz
Bartłomiej Hrapkowicz
Klaudiusz Gołombek
Małgorzata Karolus
Patrycja Janiak
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Abstract

Magnesium-based materials are promising alternatives for medical applications, due to their characteristics, such as good mechanical and biological properties. Which opens many possibilities for biodegradable materials to be used as lessinvasive options for treatment. The degradation is prompted by its chemical composition and microstructure. Both those aspects can be finely adjusted by proper manufacturing process, such as mechanical alloying (MA). Furthermore, MA allows for alloying of elements, that normally would be really hard to mix due to their very different properties. Magnesium usually needs various alloying elements, which can further increase its. Alloying magnesium with rare earth elements is considered to greatly improve the aforementioned properties. Due to that fact erbium was used as one of the alloying elements, alongside zinc and calcium to obtain Mg64Zn30Ca4Er1 alloy via mechanical alloying. The alloy was milled in the SPEX 8000 Dual Mixer/Mill high energy mill under an argon atmosphere for 8, 13, and 20 hours. It was assessed by X-ray diffraction, energy dispersive spectroscopy, granulometric analysis, and hardness. The hardness values reached 232, 250, and 302 HV respectively, which is closely related to their particle size. The average particle sizes were 15, 16, and 17 μm respectively.
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Authors and Affiliations

Bartłomiej Hrapkowicz
Sabina Lesz
Marek Kremzer
Małgorzata Karolus
Wojciech Pakieła
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Abstract

In this paper, the performance and frequency bandwidth of the piezoelectric energy harvester (PZEH) is improved by introducing two permanent magnets, which is attached to the proof mass of a dual beam structure. Both magnets are in the vicinity of each other and attached in such as a way to proof mass of a dual-beam, so that they create a magnetic field around each other. The generated magnetic field develops a repulsive force between the magnets, which improves not only electrical output but also enhances the bandwidth of harvester. The simple rectangular cantilever structure with and without magnetic tip mass has the frequency bandwidth of 4 Hz and 4.5 Hz respectively. The proposed structure generates a peak voltage of 20 V at a frequency of 114.51 Hz at an excitation acceleration of 1g (g = 9.8 m/s2). The peak output power of a proposed structure is 12.2 μW. The operational frequency range of a proposed dual-beam cantilever with magnetic tip mass of 30 mT is from 102.51 Hz to 120.51 Hz i.e., 18 Hz. The operational frequency range of a dual-beam cantilever without magnetic tip mass is from 104.18 Hz to 118.18 Hz i.e., 14 Hz. There is an improvement of 22.22% in the frequency bandwidth of proposed dual-beam cantilever with magnetic tip mass of 30 mT than the dual-beam without magnetic tip mass.
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Authors and Affiliations

Ashutosh Anand
Srikanta Pal
Sudip Kundu

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